The mystery of why we don't uninstall the last server is interesting, but all the caveats seem totally fair and understandable.
Making free Hybrid keys for Exchange 2019 is a very welcomed kind gesture. Thank you!
The Release cadence change, does seem funny how few years it takes before Microsoft changes its mind. But at this point it's clear and should be expected that there are always going to be these changes and the different products are like planets that only line up for a short period of time. Right now they're looking pretty aligned!
Next up we should expect a few product and feature name changes designed to keep everyone on their toes (especially students and exam takers). But seriously please don't 😃.